The manufacture of semiconductor wafers to create semiconductor integrated circuit devices typically involves a sequence of processing steps which fabricate the multi-layer structure generally associated with the integrated circuit devices. Such processing steps may include (1) the deposition of metals, dielectrics, and semiconductor films, (2) the creation of masks by lithography techniques, (3) the doping of semiconductor layers by diffusion or implantation, (4) the polishing of outer layers (e.g. chemical-mechanical polishing), and (5) the etching of layers for selective or blanket material removal. Hence, the manufacture of a first type of semiconductor wafer may include a large number of processing steps which are different relative to the processing steps required to fabricate a second type of semiconductor wafer. Since many different types of semiconductor devices (e.g. different part numbers) are often manufactured in the same facility, it is necessary to identify or otherwise mark each individual semiconductor wafer so that it may be distinguished from wafers of a different type. In particular, it is necessary to mark individual wafers with an identification code which includes, for example, the part number of the integrated circuit devices contained in the wafer, the date code of the wafer, and the lot number of the wafer.
One manner of marking semiconductor wafers is to scribe the identification code in the wafer via laser ablation. In particular, a focused laser beam from a laser device, such as an excimer laser device, is impinged on the front side of the semiconductor wafer so as to scribe the identification code in the front side of the wafer. For example, as shown in FIG. 8, laser scribing devices which have heretofore been designed disadvantageously scribe an identification code 100 in a semiconductor wafer 102 in a linear fashion. Hence, the identification code is not completely contained within an inactive outer clear out area 104. The inactive outer clear out area 104 is a "clear out" area which is generally not fabricated to include a resist layer or the like so as to prevent certain types of fabrication defects. Scribing the identification code such that a portion of the code is not completely contained within the inactive outer clear out area 104 has a number of drawbacks associated therewith. Firstly, the usable surface area within an active area 106 of the semiconductor wafer is undesirably decreased since a portion 108 of the identification code 100 is scribed therein. Moreover, residual resist from a photolithography step may be deposited and thereafter expelled from the pits associated with the portion 108 of the identification code 100 located in the active area 106 of the semiconductor wafer 102 thereby undesirably generating contaminants during subsequent processing steps.
In addition, in certain manufacturing processes, semiconductor wafers are sorted via use of an optical character recognition (OCR) device which reads the identification code scribed in the wafer 102. Use of such an OCR device is complicated by the differing background colors and/or topographies associated with the portion 108 of the identification code 100 which is located in the active area 106 and a portion 110 of the identification code 100 which is located in the inactive outer clear out area 104.
Thus, a continuing need exists for a wafer scribing apparatus and method which overcomes one or more of the above mentioned drawbacks.